Archive for the ‘Networking’ Category

Upgrading a Juniper J4350 to 2GB Compact Flash

Monday, March 29th, 2010

This is somewhat of an impossibility, right?  Well, not really.  Although not technically supported by Juniper, we are able to go above the recommended 1GB Compact Flash size on J-series routers (at least J4350s).

This was performed on lab equipment, not production equipment.  I wouldn’t advise doing anything that would violate any manufacturer’s support agreement on production equipment.  Use this at your own risk – your mileage may vary, especially as it’s not following Juniper’s recommendations.  Phew – disclaimer finished – now let’s move on…

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Nexus (NX-OS) protocol support (and cleanup)

Monday, March 29th, 2010

Over the years, Cisco has been very instrumental in the design and standardization of many networking protocols.  There are lots of examples where a need for a protocol was identified and Cisco filled the need with a Cisco-proprietary protocol.  Cisco-proprietary can sound bad, but it really isn’t.  Let’s give them some credit here – network equipment vendors are in competition and don’t typically play well together.  Often times vendors pitch proprietary solutions in an attempt to carve out a niche that delineates them from their competitors.

There are several standards organizations in existence today (IEEE, IETF, CableLabs, etc.) which many vendors work with and closely follow.  While this sounds ideal (and is very beneficial), standards often take a significant amount of time to be ratified, leaving any current needs unaddressed from a standards perspective.  The only alternative (for a quick resolution) is a proprietary solution, while the standards process is given time to complete. (more…)

Missing VLANs are not automatically created in NX-OS

Wednesday, February 17th, 2010

In IOS, if we assign a switchport to a non-existent VLAN, the switch will kindly create the missing VLAN for us. NX-OS does not do that – if a switchport is assigned to a missing VLAN, the interface will be placed in the down state. Let’s look at it… (more…)

FEX configs are retained

Monday, February 15th, 2010

The N5k maintains the config of the FEXs, even when they’re removed (and even though it’s not visible to us). In this article, we’re going to look into this a little further… We’ll start with a working FEX, using Po100 (with Eth1/19-20 being the physical bundle members). (more…)

Some NX-OS features can’t be manually enabled

Wednesday, February 10th, 2010

The whole idea around features in NX-OS has been intriguing to me. It’s a good idea – I like it. It seems very similar to services on many other OSs (particularly *nix systems), however it doesn’t always strike me as having a rich feature set as of now.

For instance, the NX-OS config guides repeatedly refer to the show feature command to look at which features are enabled.  I’ve already mentioned that this command doesn’t exist today in older NX-OS versions – the currently-available NX-OS versions today support this feature (a reader confirmed this on the N7k and I’ve confirmed it on the N5k).  See this article for more info.  There are some interesting behaviors around features, in that some are manually enabled, while others are automatically enabled and disabled as needed.  Let’s dig into this a little deeper for an example… (more…)

EtherChannel behavior in NX-OS

Tuesday, February 9th, 2010

I’ve had a lot of discussions with clients about the behavior of Port-Channel interfaces and their associated physical counterparts.  It’s necessary for many parameters of the physical and logical interfaces to be the same.  Here’s the behavior within NX-OS and the preferred way that I make changes to EtherChannels.

In this, we’re going to continue working with the logical interface Po100 and the physical interfaces Eth1/19 and Eth1/20 which will be in the EtherChannel. (more…)

Why EtherChannels should be used for FEX interfaces

Monday, February 8th, 2010

I prefer to use port-channel interfaces for the fabric interfaces when connecting fabric extenders (FEXs). If a single interface in the bundle fails, it won’t remove the fabric extender interface – it simply reduces it’s bandwidth. This results in stable, predictable, redundant and resilient behavior. Let’s prove this point. (more…)

Cisco WAAS – weird error when trying to register WAEs to the central manager

Friday, February 5th, 2010

When working on a WAE 500 (I know, this is really old hardware), I ran into an issue when trying to register with the central manager (CM):

waas-edge#sh cms info
Device registration information :
Device Id                            = 216
Device registered as                 = WAAS Application Engine
Current WAAS Central Manager         = 10.1.1.200
Registered with WAAS Central Manager = 10.1.1.3
Status                               = Pending(CM is busy, retry later)
Time of last config-sync             = Fri Feb  5 09:20:12 2010            

CMS services information :
Service cms_ce is running
waas-edge#

Here’s how I resolved it! (more…)

Experimenting with Static Pinning

Thursday, February 4th, 2010

What happens when more links are associated with an FEX than are permitted in the max-links parameter? Let’s find out…

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The FEX information is cached until it’s re-assigned to a different FEX

Tuesday, February 2nd, 2010

Continuing our journey into the world of FEXs on the Nexus 5000 and 2000, today we’re going to look at the behavior of the FEX configs themselves on the Nexus 5000.

All of the configuration and software information (firmware/images) for the FEX (Nexus 2148T) are kept on the parent switch (a Nexus 5000-series switch). Going on this, what happens when the FEX goes offline? Do I lose my config?

A stack of 3750 switches can be provisioned ahead of time, so that as stack members are added (assuming that they’re the correct type/model), no changes must be made – just move on. What kind of behavior is available on the Nexus 5000/2000?

I haven’t found provisioning available yet for FEXs on the N5k, however I did notice that the configurations for the FEX are retained when the FEX goes offline and online. This is great — if the 2148T fails or the fabric interface links are disconnected, the config will still be there (although not visible until the FEX comes back online). This article is looking at it from an association perspective (N2148T association with the N5k, not a configuration (actual port configs on the FEX). With that said, let’s explore this further… (more…)